This invention is related to a dyeable polyolefin composition, in particular, a polyolefin composition containing certain modifiers imparting improved acid and disperse dyeability to the polyolefin.
It is well known that articles of polyolefins are rather difficult to dye. This poor dyeability is particularly objectionable in fibers prepared from polyolefins, especially when these fibers are used in preparing primary carpet backing wherein it is desirable to have the carpet backing dyed to a shade of color which makes an acceptable comparison with the shade of color to which the pile fiber is dyed. In this use the woven or nonwoven fibrous polyolefin sheet is tufted with nylon carpet fibers to prepare a tufted carpet which is normally acid dyed at a pH of about 6 since lower pH values can lead to dye streaking of the nylon fibers. However, under these conditions the nylon carpet fibers compete with the polyolefin backing for the dye with the result that the backing becomes inadequately dyed. The need for a polyolefin composition giving acceptable acid dyeability under these conditions is particularly acute.
There have been many suggestions of methods by which the dyeability of polyolefins may be improved. U.S. Pat. No. 3,433,853, issued to Earle on Mar. 18, 1969, discloses an acid-dyeable polyolefin composition comprising 80 to 99.5% by weight of a stereoregular polyolefin and 0.5 to 20% by weight of a basic polyamide comprising the reaction product of one or more dicarboxylic acids or suitable derivatives thereof and a polyamine having not more than two primary amine groups and one or more tertiary amine groups, said basic polyamide being present in an amount sufficient to provide 0.1 to 1.0% by weight of basic nitrogen in the composition. U.S. Pat. No. 3,484,838, issued to Press on Dec. 16, 1969, discloses that improved dyeability with acid and dispersed dyes is obtained with certain stereoregular polyolefins by dispersing in the polyolefin from about 2-20% of a modifying copolymer which is hydrophilic, nonsoluble in the polyolefin, and fusible at a temperature of from 150.degree.-350.degree. C., said modifying copolymer being selected from a particular group of copolymers which includes certain copolymers of N-vinyl-2-pyrrolidone.
U.S. Pat. No. 3,505,429, issued to Press on Apr. 7, 1970, discloses a stereoregular polyhydrocarbon composition with increased dyeability comprising a matrix of a polyhydrocarbon selected from a certain group having concentrated in amorphous regions thereof a modifier combination comprising (1) 95-99% by weight of a modifying polymer containing at least 25% of an oxygen containing N-alkenyl heterocyclic monomer selected from a group of some 20 polymers which include poly N-vinyl-2-pyrrolidone homopolymer and certain copolymers of N-vinyl-2-pyrrolidone and (2) 1-5% by weight of a material selected from a group which includes polyamides such as those obtained from dimerized linoleic acid and alkylene diamines, polycaprolactam nylon, and sebacic acid/hexamethylenediamine/caprolactam terpolymer, said modifier being fusible with said polyolefin at temperatures up to 350.degree. C. The disclosed modifier combination is said to be synergistic.
None of the foregoing references are directed to the specific problem of obtaining dyeable polyolefin composition which displays acceptable dyeability when used to prepare a fibrous woven or nonwoven backing for tufted carpets. Moreover, none of these prior art compositions provides good dyeability at a pH of 6. Hence, there still exists a strong need for a dyeable polyolefin composition which provides good dyeability, particularly when the polyolefin is used to provide a fibrous carpet backing.